Thanks all for your different answers.
As I still cannot do what I want to, I finaly explain you everythings
because my first exemple wasn't a representative one ;)
So I have a function f[x,y] (0 < f <1 increasing and continuous)
It is a complicate function where y is the integral min limit.
Whatever, what I want is to have a fat answer to the question, for a
given f[x,y] and x, what is the y ?
(my function is a continuous and increasing function, so there is only
one answer to that question).
So what I want to do is to have a loop on x (between minx and maxx) and
on y (between miny and maxX !!!) to have a list of points.
The space between 2 x is linear in Log[x], and between 2 y is linear in
Log[y].
So having a list of points arranged this way : {x, f[x,y], y}, I wanted
to interpolate that to have the answer to my prob.
Now you know everythings, if any one can help I'll be glad.
If I read the help for Interpolation[data] it is written that could work
with multidemensional data {xi, yi, ... fi}. But I can't find
A way to make it work...
I cannot use ListInterpolation because I need an aranged array. In fact
I have an arrange array in x,y but so I don't know to inverse my
function and have y in function of x,f[x,y]...
Someone proposed me to use
http://www.imtek.uni-freiburg.de/simulation/mathematica/IMSweb/imsTOC/Di
fferential%20Equation%20Systems/Utilities/InterpolationDocu.html
It seems to do what I want, but... First it means every people I worked
with will have to instal it, and second I tried to use it, but I failed
(ok I am certainly not very good).
You know everythings,
Thanks,
Fabrice.